Centrifuge with interstage washing



Feb. 23, 1954 Filed May 25, 1951 R. C. RIED CENTRIFUGE WITH INTERSTAGE WASHING -'2 Sheets-Sheet 1 INVENTOR.

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ATTORNEYS Feb. 23, 1954 R. c. RIED CENTRIFUGE WITH INTERSTAGE WASHING 2 Sheets-Sheet 2 Filed May 25, 1951 INVENTOR @fii/P/"C'. H50.

@32 firm/MW ATTORN EYS.

Patented Feb. 23, 1954 CENTRIFUGE WITH INTERSTAGE WASHING Robert C. Ried, Carle Place, N. Y., assignor to Knowles Associates, New York, N. Y., a copartnership Application May 23, 1951, Serial No. 227,908

3 Claims. (Cl. 23314) This invention relates to continuous centrifuges of the type adapted to be used in separating solids and liquids and more particularly to an improved inter-stage washing means for such centrifuges. Structures embodying the invention are particularly useful in two-stage centrifuges wherein separation is effected by the cooperative action of solid centrifuge bowls and screw conveyor scrolls rotatable with respect to the bowl, such as for example, the centrifuges disclosed in the copending applications of Robert C. Ried and Chester L. Knowles, Serial No. 84,638 filed March 31, 1949, now abandoned, and application Serial No. 84,516, filed by Otto R. Kuster and Robert C. Ried on March 31, 1949. Accordingly a preferred embodiment of present invention will be illustratively described as incorporated in this type of centrifuge, although as the description proceeds. it will become apparent that the present structure may be used equally well with various other types of centrifuges.

Centrifuges such as those described in the above-identified copending applications may be used for example to effect separations of mixtures of water and relatively fine coal, e. g. minus 4 inch particles, that are produced in coalcleaning plants. In the operation of such a multi-stage centrifuge, it is often desirable to introduce a washing liquid between the stages at a point where it will mix with the partially separated solids during their inter-stage transfer. Such washingmay be desirable, for example, to remove soluble salts contained in the surface moisture on the solid particles, or to remove entrapped slimy material, or to lower the viscosity of the solid material to permit more efiicient de-liquification in the subsequent stage of the centrifuge. In order to achieve the most effective washing, it is necessary to introduce the washing liquid at approximately the point of discharge of solids from the preceding stage, thus providing the maximum time for intermingling of the solids and washing liquid and washing of the solids by the liquid before separation of liquid and solids occur in the next stage. Since in centrifuges of the type disclosed in the abovereferred-to applications the co-axial rotors rotate at relatively high and somewhat different speeds, the introduction of washing liquid at the optimum point presents a difiicult problem.

It is a principal object of the present invention to provide an improved means for introducing inter-stage washing liquid into a multi-stage continuous centrifuge. It is another object of the invention to provide inter-stage washing means that avoids the use of a revolving joint, packing gland or like mechanical seal. It is still another object of the invention to provide means for introducing wash water into a multi-stage centrifuge at approximately the point of discharge of solids from a stage other than the last stage. It isa further object of the invention to provide inter-stage washing means without using a pipe or conduit that obstructs the flow of separated solids or liquids in either stage of the machine. It is a still further object of the invention to provide for introduction of inter-stage wash water in such a centrifuge without cutting of the conveying scroll with resultant reduction in conveyor capacity. Other objects of the invention will be in part obvious and in part pointed out hereafter.

The many objects and advantages of the present invention may best be understood and appreciated by reference to the accompanying drawings which illustrate a centrifuge incorporating a preferred embodiment of the present invention and wherein:

Fig. 1 is an elevation partly in vertical section showing the general construction of the centrifuge;

Fig. 2 is a vertical section through the lefthand end of the centrifuge rotors showing the construction of the liquid-retaining channels;

Fig. 3 is a partial left-end elevation broken away to show one of the liquid retaining rings;

Fig. 4 is a perspective view of the liquid-retaining ring of the low-speed rotor;

Fig. 5 is a perspective view of the liquid-retaining ring of the high-speed rotor; and

Fig. 6 is a detailed section showing one of the washing-liquid transfer conduits.

Referring to the drawings and particularly to Fig. 1, the centrifuge there shown is a two-stage solid bowl machine comprising a pair of co-axial rotors, one of which rotates at a somewhat higher speed than the other. The low-speed rotor comprises a stepped cylindrical core I0 having mounted on the outer surface thereof a screw conveyor scroll I 2. The core 10, at its left-hand end is mounted through a head I4 on a hollow shaft I8 that extends laterally to the left through the casing N3 of the centrifuge and is supported in a self-aligning bearing 20 outside the casing. At its right-hand end the core I0 is mounted through head 22 on a hollow shaft 24 that extends through the right-hand end of casing l8. Secured to the hollow shaft l6 near the left-hand end of casing l8 and within the casing, there is an end plate or head 26 which carries at its pe- 3 riphery the tapered second-stage centrifuge bowl 28. The scroll 12 of the first stage of the centrifuge and the bowl 28 of the second stage of the centrifuge rotate as a unit.

The higher speed rotor comprises a first stage centrifuge bowl 39 that is mounted to cooperate with scroll l2 anda'second stage-scroll?! that is positioned to'co'ope'rate withthe second stage centrifuge bowl 28. The scroll 32 is mounted on a tapered core 34 which at its small end embraces and is secured to the exterior of the tapered left-hand end of bowl30. The centrifuge bowl to communicates at its tapered end with the bowl 28 through a circumferentiallyarranged series of ports or passages 38, only one of which is shown in Fig. l. The high-speed rotor, including bowl 3!) and scroll 32,'is mounted atits left-hand end through a head 38 and bearing on hollow shaft 18. At its right-hand end the high speed rotor is mounted through head 42 and" hollow shaft l l in a self-aligning bearing d6, loeated outside the centrifuge casing 18.

Todriye therqtors, the'hollow shaft is provided near'its left'end with a pulley 18 which may be driven by a multiple v-belt froma suitable power source (not shown). The low-speed rotor is'drivendirectly throughpulley 48 and the high-speed rotor indirectly therefrom. Referring to the right-hand portion of Fig. l, the hollowshaftidjs keyedto a shaft 56, and the hollow shaft 458 is secured to the housing 52 of a gear mechanism (not shown). The shaft 59 and housing 52 are interconnected by a gear mechanism described in detail in theabove-referredfto-application Serial No. 84,5l6 in such manner that the high-speed rotor is driven a few revolutions per minute faster than the low speed rotor.

"mixture of liquid ands'olids to be separated en ters the machine atthe left-hand end thereof through a pipe 5 4 that extends through the hollow" shaft 18 to the feed chamber 58. It then passes through the hole 58 to the interior (sitter 3flwhi ch isr'otating at a somewhat higher speed scroll l2. The bowl 38 and scroll IQ cooperate to cause liquid'toflow to the righthaifd end of beer Eil'and be'di scharge'd through the first 'stageliduid discharge pas age; Gil. The partiallysepa'rated solids new to the left and pafisthrohgh the poi'ts'SiS to the second-stage bowl iil -wherein a' furthersparation takes place. Inthesooiidstageoolidsmove toward the right and are discharged "from thamachine through solids dischargepassage 82. Separated liquid flows to the left ahdpasses through one of a series of liquid 'seal'chamberslid whereupon it is discharged from tlieinacliine through secondst'age' discharge pas'sagess. The seal chambers army he of the type disclosed a'nd'cla'im'ed-in my "co' peh ding application "Serial No. 2271909, filedhn'the same day as the present application.

Referring now to Figures 2am: '3, washing liqiiid is supplied to'the machine from a suitable source ('nctshown) through'apipe l9 ha'ving'a regulating valve "12 therein. The pipers, as shown'in Fig.2,exterids through the casing m andterininates'a short distancefrom the'end plate "2-5 "of the low s'p'e'ed' rotor. Mount'ed on the' en'd-plate 26.5 there is a ring '14 (also shown in Fig.4) which'cooperates with'end plate to' formanahnular'channel 16. The ring T4 issecu'i'ed t'o'end plate 25 'by'a series of triangular plates'ltthat'are welded toftlie rmg'an 'end platerespectively. When the centrifuge is in operation; washing "liquid "that news -tnrbug'n pipe 10 is thrown outwardly into the channel 16 and is retained therein by centrifugal force.

Secured to the larger end of scroll support 34 there is a second ring (also shown in Fig. 5) which cooperates with the scroll support 34 to define a second channel 82 adapted to contain a-body-of the "washing liquid when the' centrifuge inope'rati'on. Transfer of washing liquid from channel 16 to channel 82 is effected by means of the liquid-transfer conduits 84. Referring particularly to Fig. 6, the conduits 84 are securedinthe er'id'plate 2B and are provided with the notches 6 -atytheir inner ends to permit passage" of liquids 'therethrough. The discharge notches 86 as "shown in Fig. 2 are positioned within the margin of the scroll support 34 and hence 'durin'gop'eiation of the centrifuge liquid flowing through the conduits 84 is thrown outwardly into channel 82.

The scroll support, is provided adjacent to each passagetfi with the ports or holes88 which communicate with the'wa-shing liquidfin'channel 82 and serve to permit "flow of the washing liquid to the separating space 'of the second stage ofth'e centrifuge and 'to produce intermingl'in'g 'of the vashing liquidwith the solids flowing through the passages 35. L

From the foregoing description it is apparent that the present invention provides astructures capable is achieving the several object's 'outlined above. The washing liquid is brought are contact with the inter-stagesolids'as'they enter the 'separaungspaee of thesecoiid stage of the centrifuge and th'e'reforean adequate 0P1 tunity for mixing and'wa'sh'i'ng is'provide'd. The washing liquid flows from a istationarysou'rce to the rapidly moving ports 58' smoothly and uniformly and Without the interposition ofar iy revolving joint or mechanical "seal. Moreover it is introduced under such conditions thatit does'not interferewith movement of either 'solids or liquid in eitherstage of the machine. Convenient regulation of the rate of f'supply"of washing liquid isachived by means'of 'thevalv'en. Itis evident'thatmore than'one pip'e'lll'fmay' be provided if desired and a number of washing liquids supplied eithfsimultaheously or sequentially.

It is of course to be understoodthat the foregoing des'c'ription'is illustrative andthat numerous changes might be made inthespecific' structure described *without departing "from thesco'pf'e of the invention as defined in the appended claims. 7

What is claimed as new is:

1. A-two stagecentrifuge-'adapted'to be used in separating a particulate solid material from a liquid comprising, in combination, a first rotor including a first-stage centrifugebowl'and' asecond-stage' conveyor 's'c'rollj'a second rotor 'fjcoaxial withsaid first'rotor and including a firststage conveyor" scroll adjacent to the inn'er' surface of said iirstgst'a'g'e 'bowl and a second-stage bowl embracing I said second-stage scroll, said first stagebowl andscroll being located'at least partially-withinsaid second stage sc'rolland bowl,

driving means for driving saidtwo rotors 'at" different speeds, whereby each of said centrifuge bowls cooperates-with itsfadjacentscroll to effect at leasta partialfseparation "of "said fsol'id material and liquidfthefsolids"discharge end'ofsaid firstrotor being provided withaplii'rality of assages for 'oonduct'ingsaid solidniaterialto safe sec'ond -stagebowl" nd' 'the liqui dischargeendof said scond's'tage w fb'eimg provided wit an enablers,a firt aifmnsrririghiounfidansaid end plate and cooperating therewith to define a first liquid-retaining channel, means for supplying a washing liquid to said channel, a second annular ring mounted at the solids discharge end of said first rotor and cooperating therewith to form a second liquid-retaining channel, a plurality of conduits communicating with said first channel and extending through said end plate to a point opposite said second channel, and a port adjacent to each of said passages and interconnecting said second channel and the second stage separating space of said centrifuge whereby washing liquid can be supplied to said solid material as it passes from the first to the second stage of said centrifuge.

2. A centrifuge according to claim 1 and wherein said rotors are encased in a housing, said washing liquid-supply means is a conduit extending through said housing to a point opposite said first channel and said conduit is provided externally of said housing with a regulating valve for regulating the quantity of washing liquid supplied to said solid material.

3. A two-stage centrifuge adapted to be used in separating a particulate solid material from a liquid comprising, in combination, a first rotor including a first-stage centrifuge bowl having a tapered solids discharge end, a second-stage conveyor scroll, a tapered support for said secondstage scroll embracing the tapered end of said first-stage bowl and a plurality of passages interconnecting the tapered end of said first bowl with said tapered support for conducting solid material from said first-stage bowl to said second-stage scroll; a second rotor co-axial with said first rotor and including a first-stage conveyor scroll adjacent to the inner surface of said firststage bowl and a second-stage bowl embracing said second-stage scroll; driving means for driving said two rotors at difierent speeds whereby each of said centrifuge bowls cooperates with its adjacent scroll to effect at least a partial sepa ration of said solid material and liquid and causes separated solid material to flow through said passages, the liquid discharge end of said secondstage bowl being provided with an end plate; a first annular ring mounted on said end plate and cooperating therewith to define a liquid-retaining channel; means for supplying a washing liquid to said first channel; a second annular ring aifixed to the larger end of said tapered scroll support and defining therewith a second liquid-retaining channel, a plurality of conduits communicating with'said first channel and extending through said end plate to a point opposite said second channel for conducting liquid from said first channel to said second channel, said scroll support being provided adjacent to each of said passages with a plurality of ports communicating with said second channel, whereby washing liquid can be supplied to said solid material as it flows from the first to the second stage of said centrifuge.

ROBERT C. RIED.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,806,241 Dupuis May 19, 1931 2,184,598 Jahn Dec. 26, 1939 2,283,457 Pecker May 19, 1942 FOREIGN PATENTS Number Country Date 319,337 France July 10, 1902 

